Allergic encephalomyelitis is a central nervous system disease of immunologic origin. In juvenile strain 13 guinea pigs, cataracts developed during severe allergic (autoimmune) encephalomyelitis syndromes produced actively or by transfer of living lymph node cells from sensitized strain 13 donors. These lens changes were manifested bilaterally within a two-week period of active sensitization or transfer of sensitized cells. The morphologic in vivo appearance of these cataracts is similar to both the galactosemic-induced and tryptophan deficiency cataract models. A better understanding of the etiology of these lesions not seen before in this entity in guinea pigs will help in understanding cataract formation in systemic disease.